Sheave assembly



T. B. APPEL, JR

SHEAVE ASSEMBLY July 14, 1953 Filed Jan. 27, 1951 INVENTOR. Theodore B. @1508], J):

Zr/Illllf llq M Al Patented July 14, 1953 VUNHTED STATES PATENT OFFICE SHEAVE ASSEMBLY Theodore B. Appel, In, Champaign, 111., assignor to The C. S. Johnson Company, Champaign, 111., a corporation of Illinois Application January 27, 1951, Serial No. 208,161

6 Claims. l

The improved sheave assembly comprising the present invention has been primarily designed for use in connection with concrete mixing in stallations wherein it may be employed, for example, as a cable guide for changing the direction or pull of a steel cable in a cable system leading from one of the pull rods of a batcher control mechanism to the long arm of a weighing scale or other measuring device. The invention is capable, however, of other uses and the same may, with or without modification, be employed in a wide variety of installations for changing the direction of pull of a cable wherever the displacements involved are relatively small and where it is desired to reduce friction to a minimum.

It is among the principal objects of the present invention to provide a sheave assembly in the form of a cable guide which will reduce friction to a minimum and which is therefore admirably well adapted for use in connection with cable systems leading to sensitive or delicate precision recording instruments where the friction incidental to the installation of ordinary sheaves would lead to inaccurate dial or pointer readings.

Another object of the invention is to provide a sheave construction having a knife edge bearing support for the sheave proper which presents practically no dust collecting surface which would otherwise accumulate frictional resistance and interfere with the free movement of the cable over a period of time. By such an arrangement, the present sheave construction is well adapted for use in connection with concrete and other batcher installations as illustrated herein despite the heavily dust-laden atmosphere peculiar to such installations.

A still further object of the invention is to provide a sheave construction of the character outlined above which may be readily assembled or disassembled for the purposes of adjustment or repair and which is capable of initial assembly and adjustment at the scene of installation with a minimum of effort or skill.

Another object is to provide a sheave construction including a sheave proper and a supporting bracket therefor and including a knife edge bearing on the sheave and a knife edge support on the bracket, together with means for maintaining the knife edge bearing centered upon its support against dislodgment, while at the same time presenting no frictional considerations insofar as the relative movements between the knife edge and centering means are concerned.

Yet another object is to provide a sheave construction in which the centering means mentioned above serves as a retaining means for preventing separation of the sheave proper and its supporting bracket in the event of dislodgment or breakage of the guided cable.

The provision of a sheave construction of the character outlined above which, despite its sensi tivity to cable displacements, is rugged and durable and consequently unlikely to get out of order; one which is comprised of a minimum number of moving parts; one which may be menufactured at a relatively low cost, and one which after initial assembly and installation, is well adapted to perform the services required of it over a long period of time without adjustment or repair, are further desiderata that have been borne in mind in the production and development of the present invention.

In the accompanying single sheet of drawings forming a part of this specification, one embodiment of the invention has been shown.

In these drawings:

Figure 1 is a fragmentary side elevational view, partially schematic in its representation, of a batcher control installation involving a pull cable to which a number of the improved sheave constructions comprising the present invention have been applied.

Fig. 2 is a side elevational view of a sheave assembly constructed in accordance with the principles of the present invention and showing the same applied to a pull cable.

Fig. 3 is an end elevational view of the structure shown in Fig. 1. In this view certain parts have been broken away to more clearly reveal the structure involved.

Fig. 4 is a sectional view taken substantially along the line 44 of Fig. 2.

Fig. 5 is a sectional view taken substantially along the line 5-5 of Fig. 2.

Fig. 6 is a sectional view taken substantially along the line 6-6 of Fig. 7, and

Fig. '7 is a perspective view of a sheave insert and bearing support employed in connection with the present invention.

Referring now to the drawings in detail and in particular to Fig. 1, for illustrative purposes three of the sheave constructions of the present invention are shown in operative position in a batcher control installation for the purpose of guiding a cable leading from a weighing scale to one of the pull rods leading to a control device contained within a batcher control cabinet. Such a control mechanism is shown and described in the patent to Martinson, No. 2,559,307,

dated July 3, 1951, for a Batcher Control Mechanism.

The control cabinet is designated in its entirety at [8- and may be substantially identical with that shown and described with the above mentioned patent to Martinson. Accordingly, a series of pull rods, one of which is shown at 12 project upwardly from the top of the cabinet, and each rod adapted to be connected through a cable E4 to the long arm [6 of a pivoted scale beam B. The pull rod I2 is operatively connected within the cabinet ID to suitable control devices (not shown) which may have associated therewith indicating and recording instrumentalities as shown in the above mentioned patent. The weight W to be measured is applied to the short arm l8 of the pivoted scale beam B.

The pulley and sheave assemblies comprise the present invention and are designated in their entirety at 2!], one such assembly being positioned substantially directly above the cabinet 60 and suspended from a support 22; another being located below the level of the first assembly and being suspended from a support 25, and a third assembly being located a substantial distance from the cabinet l and below the long arm is of the scale beam B and carried on a support 25. The first assembly accommodates an approximate 148 direction change in the cable M. The second assembly accommodates approximately 50 direction change, while the third assembly accommodates an approximate 98 direction change. The above direction change angles have been selected for illustrative purposes only, and ob viously they may be varied widely to accommodate other installations.

Referring now to Figs. 2 to 5, inclusive, each assembly involves in its general organization a sheave proper which may be in the form of a relatively thin, flat circular disk having a grooved peripheral edge 30 designed to accommodate reception therein of that portion of the cable M with which the sheave 28 comes into contact. The sheave 28 is provided with a hub portion 32 which is concentric with the center of the disk, which hub portion is provided with a central opening 34 extending therethrough.

The disk 28 may be formed of any suitable material but preferably it is formed of aluminum. A hardened steel insert 35 has a pressed fit in the opening 34 and includes a central body portion 38 from which there projects laterally on each side thereof a knife edge extension 49 which is generally triangular in cross-section (see Figs. 6 and 7). The knife edge extensions 4-9 are integrally formed with the central body portion 38 of the insert 38 and are preferably in the form of sectors extended beyond the opposite faces of the body portion 38. Each knife edge extension provides a relatively sharp knife edge 42, the two knife edges being in alinement and extending substantially along the central axis of the disk 28. The extreme ends of the knife edge extensions are relieved or cut away as at 44 on an incline with respect to the adjacent side surface of the sheave disk 28 for a purpose that will be made clear presently.

The sheave proper is adapted to be pivotally supported in a sheave bracket designated in its entirety at B and which is in the form of a generally rectangular cage-like frame having elon gated sides 54 and relatively short ends 56 and 58 connecting the sides 54 and maintaining the latter spaced from each other. The sides 5d at one end thereof are provided with a pair of offset attachment ears or lugs 60 which project beyond the end 58 of the frame in spaced relationship and by means of which the bracket 5) may be secured to a supporting fixture in the form of a supporting block 62 having an outwardly projecting attachment stud formed thereon. The stud 64 is threaded as at 66 and is adapted to threadedly receive thereon a clamping nut 68 and washer it for the purpose of securing the block to a suitable support, as for example, one of the supports 22, 24 or 23 of Fig. l.

The attachment ears 60 have formed therein a pair of alined holes or openings l2 and an assembly pin 14 which passes through the block 82 and openings 72 and serves to permanently connect the bracket 50 to the block 62.

As will be explained presently, the angularity of the supporting bracket 50 relative to the support ing block 62 may be varied to accommodate different installations and, when the predetermined angularity has been established for a particular installation, the block 62 may be brazed, welded, cemented or otherwise secured to the attachment ears 60 so that these ears, and consequently the bracket 50 of which they form a part, will not change their relative position during subsequent use of the sheave assembly.

Each of the sides 5-1 of the bracket 55 is pro vided with a transverse slot 16 extending inwardly from one edge thereof and which communicates with a preferably rounded opening 58, the two openings in the side members 54 being in substantial axial alinement. One side or region of each opening '58, and preferably a region remote from the end 58 and adjacent the end 58 of the bracket, is relieved or cut away to provide a V-shaped notch or seat 88 having straight sides and a linear bottom 82. The notch 89 extends uniformly across the thickness of the metal of the side 54 in which it is formed and the linear bottom 82 thereof constitutes a supporting surface which is reduced to very sharp, thin-line proportions in order that the knife edge 42 of one of the extensions 40 of the insert 36 may rest thereon when the sheave proper 28 is installed within the supporting bracket 59.

The slots 16 in the sides 54 of the frame 52 constitute entry keyways for passage of the extensions 40 therealong so that these extensions may be introduced into the openings and thus brought into proper register with the V-shaped notches existing at the sides of the openings 18 during initial assembly of the sheave proper in the supporting bracket 50.

A pair of fiat retaining plates 90 are secured by means of screws 92 to the outer side surfaces of the side members 54 and each plate 90 is provided with an inturned lug or finger 94 which extends across and blocks the extreme ends of the slots 16 for retaining the extensions 40 within the openings 18 against dislodgment. As a consequence, the plates 90, when in position, prevent separation of the sheave proper 28 from the bracket 50 in the event the sheave becomes loose within its bearing supports due to breakage or dislodgment of the cable l4. The plates 90 may be formed of brass or other suitable material and, when they are secured in position on the outer sides of the respective side members 54 to which they are applied, the linear distance between the opposed inner faces of the plates is substantially equal to the overall linear extent of the insert 36 together with its extended knife edge portions 40. Because of the fact that the outer ends of the extensions 40 are relieved as at 44, the extensions 40 are adapted to bear against the inner opposed surfaces of the plates 90 at substantially the exact center of the disk-like sheave proper 28. Since the exact center of any disk does not rotate, very little, if any frictional resistance to turning movement of the sheave proper 28 within its supporting bracket 58 is offered during rotation of the sheave proper when in use.

Referring now to Fig. 1 wherein a number of the sheave constructions of the present invention are shown in operative cable guiding position in a batcher control assembly, it is to be noted that the angularity of each of the cage-like brackets 01' frames 58 with respect to the supporting block 62 varies according to the vectorial component of thrust exerted by the converging cable strands leading to the sheave proper. As a general rule, the longitudinal axis of the bracket 58 will extend along a line which bisects the angle subtended by the two converging cable strands. In the actual installation of the individual sheave constructions, the proper angularity of the axis of the sheave bracket 50 with respect to its supporting block 62 may be calculated according to engineering exigencies and aproper setting of the two parts effected by swinging the bracket about the axis of the pivot pin 62. Thereafter the attachment ears 6!) which project beyond the end 58 of the frame in spaced relationship may be welded or brazed a at 96 to the adjacent sides of the block 62 and, additionally, the block itself may be welded or brazed as at 93 to the end 58 of the cage or frame 50 by the application of brazing material to the space existing between these two parts.

It is to be noted from an inspection of Fig. 1 that the sheave assembly may be installed upon a support with the sheave supporting bracket 50 arranged in any desired position of angularity with respect to the vertical. The cable It may be applied to the sheave proper 25 soas to exert a tensional stress upon the cage-like bracket as illustrated in connection with those assemblies which are attached to the supports 22 and 26. In the former instance, the supportin block 82 is suspended beneath the support 22, and in the latter instance the supporting block 62 is inverted and mounted upon the support 26. In the case of the sheave assembly which is suspended from the support 24, a compressional stress is applied to the supporting bracket 50.

A more convenient method of installing the sheave constructions in a system where only tensional stresses on the bracket 5b are involved as to attach the sheaves by means of the stud and nut assemblies S R, 68 in position on the respective supports from which the sheave is to be suspended or on which it is to be mounted and to thereafter apply the cable in position. In this manner, the brackets will assume approximately the desired angularity and thus the brackets may be marked for subsequent welding or they may be welded,

brazed or otherwise affixed to the supporting block structures 62 while the cable It remain in suspended position in the assembly.

When the sheave assembly is designed for use in connection with delicate or sensitive recording apparatus, it may be found advantageous to statically balance the sheave proper on its knife edge supports prior to installation of the assembly. In order to accomplish this, a portion of the metal of the sheave disk may be removed at an appropriate location until a condition of balance of the sheave on its knife edge supports is attained.

While the disk 28 comprising the sheave proper has been described as being preferably formed of aluminum, it is obvious that other materials may be employed if desired. In certain installations the metal, aluminum, is subject to the deleterious effects of corrosion due to the presence of certain chemical gases or suspensions in the atmosphere. In such instances it is contemplated that the disk 23 shall be made of a suitable plastic or other material not subject to such destructive influences. Not only is it contemplated that a wide variety of materials may be employed 'in the manufacture of the disk 28 but also the material from which the knife edge as well as the knife edge support are formed may be varied to accommodate the particular conditions of use.

The invention is not to be limited to the exact arrangement of parts shown in the accompanying drawing or described in this specification, a various changes in the details of construction may be resorted to without departing from the spirit of the invention. Only insofar as the invention has particularly been pointed out in the accompanying claims is the same to be limited.

I claim as my invention:

1. A sheave assembly comprising a sheave in the form of a flat, circular disk having a circumferential groove in the periphery thereof providing a tractional cable guide, two projections extending outwardly from the disk on opposite sides thereof in the medial regions of the disk, each of said projections being provided with a knife edge coincident with the transverse axis of the disk. a cage-like supporting bracket, said bracket including a pair of side members adapted to straddle the sides of the disk, end members maintaining said side members in spaced relationship, each of said side members being provided with a slot in the medial region thereof extending inwardly from one side thereof, there being an opening in each side member communicating with its respective slot, said openings being in substantial alinement, there being a recess formed in the of each opening providing a knife edge support for one of said knife edges, the overall axial extent of said projections being greater than the distance between the opposed surfaces of said side members, and said slots serving as guideways to permit insertion of said projections into said openings to permit registry and contact between said knife edges and said knife edge supports.

2. A sheave assembly comprising a sheave in the form of a flat, circular disk having a circumferential groove in the periphery thereof providing a tractional cable guide, there being a central opening formed in said disk, a cylindrical insert disposed within said opening and fitting tightly therein, generally axially extending projections extending outwardly from opposite ends of said cylindrical insert and projecting beyond the planes of the respective sides of said disk, each projection being provided with a knife edge coincident with the center of gravity of the disk, a cage-like supporting bracket comprising a pair of side members adapted to straddle the sides of the disk, end members maintaining said side members in spaced relationship, there being a slot in the medial regions of each side member extending inwardly from an edge thereof, there being an opening in each side member communicating with a respective slot, said openings and said slots being in substantial alinement with each other, there being a recess formed in the side of each opening providing a knife edge support for one of said knife edges, the overall axial extent of said projections being greater than the distance between the opposed surfaces of said sides, said slots serving as guideways to permit insertion of said projections into said openings to permit registry and supporting contact between said knife edges and said knife edge supports.

3. A sheave assembly comprising, in combination, a sheave in the form of a fiat, relatively thin, circular disk having a circumferential groove in the periphery thereof providing a tractional cable guide, projections extending outwardly from the disk on opposite sides thereof in the medial regions of the disk, each projection being provided with a knife edge coincident with the center of gravity of the disk, a cage-like supporting bracket including a pair of spaced side members adapted to straddle the disk in close proximity to the sides thereof, there being an opening in each side member in the medial region thereof, said projections extending into said openings, the knife edges thereof being adapted for support on the sides of said openings, a retaining plate removably secured to each side member at the outer side of said bracket and overlying the opening formed within the side member, the overall extent of said projections being substantially equal to the distance between said retaining plates, and the ends of said respective projections being relieved axially and laterally from said knife edges whereby the ends of the projections make point contact with said retaining plates at points coincident with the axis of the disk-like member.

4. A sheave assembly comprising, in combination, a sheave in the form of a flat, relatively thin, circular disk having a circumferential groove in the periphery thereof providing a tractional cable guide, projections extending outwardly from the disk on opposite sides thereof in the medial regions of the disk, each projection being provided with a knife edge coincident with the center of gravity of the disk, a cage-like supporting bracket including a pair of spaced side members adapted to straddle the disk in close proximity to the sides thereof, there being a slot in the medial re gion of each side member extending inwardly from an edge thereof, there being an opening in each side member communicating with said slot therein, said openings and said slots being in substantial alinement with each other, a portion of each side member at one side of the opening therein providing a knife edge support for one of said knife edges, a retaining plate removably secured to each side member at the outer side of said bracket and overlying the opening formed within the side member, the overall extent of said projections being substantially equal to the distance between said retaining plates, the ends of the projections being relieved axially and laterally from said respective knife edges and making point contacts with said retaining plates, the points being coincident with the axis of the disklike member, and inturned lugs on said respective plates obstructing the entrance to said slots for retaining said projections within the spaces defined by said slots and openings.

5. An anti-friction sheave assembly comprising, in combination, a pivotal member defining an arcuate edge thereon adapted to receive a flexible tension member in guided relation thereto, two support trunnions projecting outwardly from opposite sides of said pivotal member and forming a pair of similar knife edge fulcrums defining a common pivotal axis extending approximately through the center of curvature of said arcuate edge, a sheave support bracket including two spaced generally parallel side members adapted to be disposed in straddling relation to said pivotal member, each of said side members having a medial portion defining therein an opening extending therethrough and a V-shaped seat at one edge of the opening, the openings and seats of said two side members being disposed in registry with each other, and each of said side member portions defining a generally lateral slot extending inwardly from one marginal edge thereof to the opening therein, said pivotal member trunnions being adapted to be engaged with said seats of said respective side members by movement transversely through said side member slots.

6. An anti-friction sheave assembly comprising, in combination, a pivotal member definin an arcuate edge thereon adapted to receive a flexible tension member in guided relation thereto, two support trunnions projecting outwardly from opposite sides of said pivotal member and forming a pair of similar knife edge fulcrums defining a common pivotal axis extending approximately through the center of curvature of said arcuate edge; a sheave support bracket including two spaced, generally parallel side members adapted to be disposed in straddling relation to said. pivotal member; each of said side members having a medial portion defining therein an opening extending therethrough, said side member portions each including means defining a V- shaped seat medially disposed in the plane thereof at one side of the opening therein; said openings and seats of said two side members being disposed in registry with each other, each of said side member portions defining a generally lateral slot extending inwardly from one marginal edge thereof to the opening therein, said pivotal m m ber trunnions being adapted to be engaged with said seats of said respective side members by movement transversely through said side member slots, and retainer plates detachably secured to said respective side members for blocking said slots therein.

THEODORE B. APPEL, JR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,851,110 Pellischek Mar. 29, 1932 FOREIGN PATENTS Number Country Date 7525-04 Great Britain .d Feb. 2, 1905 459,163 Germany Apr. 28, 1928 

